Di Maio, D; Willis, B; Hunt, C (2008) Measurements of copper dissolution in lead-free solder alloys. NPL Report. MAT 26

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Abstract

The transition from tin-lead to lead-free has increased the tendency for copper dissolution in molten solders. PCB land and plated through holes can be eroded or dissolved away in the presence of molten solder rendering the PCB non-functional. Significant dissolution can potentially occur with certain tin-rich alloys due to increased solubility of copper, which is further exacerbated by the higher process temperatures. Clearly this phenomenon represents a serious risk to circuit reliability. To determine the dissolution rate of copper in lead-free solders, a well defined and efficient technique has been developed to compare solder performance.

The first phase of this project developed a measurement method for copper dissolution rates under a variety of conditions and with many different commercial and reference alloys. Here a special PCB design and thickness erosion timing technique was developed. This methodology provided repeatable measurements that allowed the various experimental parameters to be isolated. These findings were tested in a second phase using a circuit board with assembled parts to assess the copper thickness after selective and hand soldering processes performed using various commercial alloys.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MAT 26
Subjects:	Advanced Materials
Last Modified:	02 Feb 2018 13:15
URI:	http://eprintspublications.npl.co.uk/id/eprint/4353

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